steam_workshop_subscribe_page_v1.js

// ==UserScript==
// @name        steam_workshop_subscribe_page_v1.js
// @namespace   Violentmonkey Scripts
// @match       https://steamcommunity.com/workshop/browse/*
// @grant       none
// @version     1.0
// @author      Gesugao-san
// @description huh
// ==/UserScript==

'use strict';

(function () {
  console.log('Match!');
})();

//if (window.location.hostname != 'steamcommunity.com') throw "Wrong page.";
//if (window.location.pathname != '/workshop/browse/') throw "Wrong path.";

const sleep = sec => new Promise(r => setTimeout(r, sec*1000));
const subs_get = () => document.querySelectorAll('span.general_btn.subscribe:not(.toggled)');
const subs_count = () => subs_get().length; // [...subs_get()]
async function subs_set() {
  console.log("Subs available:", subs_count());
  await subs_get().forEach(async (button) => {
    var sleep_var = Number((Math.random()).toFixed(5))*4+1
    await sleep(sleep_var);
    console.log("Subscribing to:", button.id.split('Btn')[1], "sleeping:", sleep_var);
    button.click();
  });
}

const scrolls_get = () => document.querySelectorAll('a.pagebtn:not(.disabled)');
var scrolls = scrolls_get();
const scrolls_count = () => scrolls.length;
const scrolls_set = () => {
  scrolls_get().forEach((button, index) => {
    scrolls[index].innerHTML == '>' ? scrolls[index].click() : null
  })
};

async function main() {
  await subs_set();
  await sleep(15);
  await subs_set();
  scrolls_set();
}

HTMLDocument.prototype.ready = new Promise((r) => {
  if (document.readyState != "loading") return main();
  else document.addEventListener("DOMContentLoaded", () => {return main()});
});

document.ready.then(() => {console.log("document ready")});

steam_workshop_subscribe_page_v2.js

if (window.location.hostname != 'steamcommunity.com') return console.error("Wrong page.");
if (window.location.pathname != '/workshop/browse/') return console.error("Wrong path.");

var inputs = document.querySelectorAll('[data-publishedfileid]');
for (var i = 0; i < inputs.length; i++) {
  var id_str = inputs[i].dataset.publishedfileid;
  var id_int = parseInt(id_str);
  var is_faved = (inputs[i].parentElement.getElementsByClassName('user_action_history_icon favorited').length == 1);
  VoteUp(id_int);
  if (!is_faved) FavoriteItem(id_int);
  SubscribeItem(id_str, '294100');
}
var nextp = document.querySelectorAll('a.pagebtn:not(.disabled)'); // https://stackoverflow.com/a/38788621/8175291
if (nextp.lenght != 1) return console.log(nextp);
nextp[0].click();